The present invention relates to a thermoelectric thermometer for measuring the temperature of a hot object, such as the molten metal in blast furnaces or smelting furnaces or metal being heat-treated for hardening or tempering.
Generally, there arises a need to detect the temperature of an object at a location away from the position of temperature measurement for controlling the temperature of the object according to the detected temperature.
For measuring high temperatures (e.g. 300.degree. C. to 1300.degree. C.), a thermoelectric thermometer is used which comprises a thermocouple. One junction of the thermocouple is held at 0.degree. C. or room temperature to measure the thermoelectromotive force developed in the thermocouple, whereby the high temperature can be measured accurately.
However, the environment in which such a high temperature is to be measured is hot, hazardous and not readily accessible, so that it is difficult to frequently measure the temperature in the adverse environment for the control of temperature.
Accordingly, it is conventional practice to connect the thermocouple, serving as a measuring instrument, to an indicator by a compensation conductor to indicate the temperature at a location away from the hot object.
Nevertheless, there is a limitation to the length of the compensation conductor which is invariably needed for thermometers of the thermocouple type since the thermoelectric thermometer is adapted to measure temperatures by measuring the thermoelectromotive force in the thermocouple.
Stated more specifically, an increase in the distance between the thermocouple and the indicator requires a longer compensation conductor, making it impossible to accurately indicate the measured temperature owing to the influence of the conductor resistance and the influence of the temperature difference between the position of measurement and the position of cold junction compensation.
Furthermore, it is impossible to increase the number of indicators easily or to shift the indicator because it is then necessary to shift the compensation conductor similarly.